In order to mount, for instance, a telephone-type hand shower on the wall so that it can be used like a stationary shower head, it is standard to provide a separate fork-shaped bracket that is fixed to the shower wall. Since the walls are typically made of tile, it is necessary to bore at least one hole in the wall, fit a lead or plastic anchor therein, and then secure the bracket to this anchor by a screw.
This type of installation creates a potential leak site in the otherwise waterproof wall, a place where water can get past the waterproof covering formed by the tile to the underlying structure which could be damaged by water. Since the wall is of a hard ceramic, it is unlikely that the hard metal or plastic bracket will fit it accurately, so that some water will surely get between the bracket and the wall. Furthermore the fact that this area is closed means that the water that gets behind the bracket is trapped just at that location where it can work its way into the hole in the wall.